JP2695554B2 - Stretch film for grass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stretch film for wrapping grass, which is optimum for stretch-wrapping roll-veiled grass used as feed for horses and cattle and obtaining silage having high nutritional value by fermentation. Is.

[0002]

2. Description of the Related Art Conventionally, many preparation techniques have been established based on the basic theory for the method of fermenting grass to increase its nutritional value and using it as a feed for livestock. But the bag,
When the tube is used as a packaging material, labor saving by mechanization could not be performed from harvest of grass to packaging and silage preparation. Furthermore, since the products packaged with these have poor hermeticity and it is difficult to completely block outside air, there is a high risk of aerobic fermentation and mold formation. Therefore, in recent years, a method of packaging roll-veiled grass with a stretch film has begun to spread. Although this method requires a large machine, it can be operated by one person from harvesting to silage preparation, and is becoming popular among dairy farmers who are underhanded.
According to this roll bale packaging method, when the veiled raw grass is hermetically packaged with a stretch film, the inside of the bale becomes anaerobic within a few hours if good packaging is performed.

[0003]

The stretch film conventionally used for roll bale packaging has poor quality and has the following problems. (1) Wrinkles are easy to enter and the adhesiveness is low, so that air is not mixed into the veil to make it anaerobic, or once anaerobic, it becomes aerobic again and rots to cause rot May not be used as. (2) The impact resistance is low, and the film is punctured by the stalks of grass during packaging, so that fermentation is not performed well and high quality silage cannot be obtained. (3) Since little consideration is given to weather resistance, it is difficult to maintain airtightness for a long period of time when the silage is prepared by leaving it outdoors. (4) There is a difference between the shrinkage rate in the longitudinal direction of the stretch film and the shrinkage rate in the direction orthogonal to it (5% or more).
The film width of the outer circumference becomes narrow, and the product is rolled up (1800m per roll, width 500mm, thickness 25μ)
Is deformed. For this reason, it may be difficult to use it in a wrapping machine for grass, and when pulling out the film, the force to pull out the film inside may act, and the film may break.

As a high quality stretch film in which the problems of the conventional stretch film are reduced,
For example, Japanese Patent Publication No. 2-12187 and Japanese Patent Publication No. 2-18
There is a stretch film described in Japanese Patent No. 983. This comprises a first layer containing an ethylene-α-olefin copolymer as a main component and a second layer containing an ethylene-vinyl acetate copolymer as a main component, and if necessary, a lubricant such as oleic acid amide. It is a stretch film having a two-layer structure in which a small amount of an inorganic filler such as talc or silica, and an adhesive such as a low molecular viscous substance of polybutene is added.

However, this Japanese Patent Publication No. 2-12187
The stretch film described in Japanese Patent Publication No. 2-18983 and Japanese Patent Publication No. 2-18983 was originally developed for pallet stretch for accumulating and packaging canned beverages, books, or miscellaneous goods. When used for roll bale packaging, it cannot be said to be sufficiently satisfactory in terms of concealing property, weather resistance and the like. The present invention has been made in view of such circumstances, and an object of the present invention is to obtain suitable tackiness, impact resistance, shrinkability, and Japanese adhesiveness for packaging grass using a grass wrapping machine. (EN) It is intended to provide a stretch film for wrapping grass having weather resistance suitable for climate.

[0006]

According to the present invention, ethylene and .alpha.-olefin are copolymerized and the melt flow rate is 0.4 to 3.0 g / 10 minutes and the density is 0.90.
The main component is 0 to 0.930 g / cm ³ linear low density polyethylene, and the melt flow rate is 0.2 to 5 g.
/ 10 minutes, the density is 0.916 to 0.930 g / cm ^3.
5 to 25% by weight of high-density low-density polyethylene, 1.5 to 5% by weight of carbon as a pigment, or 3 to 7 of TiO ₂
% By weight, a first layer comprising a composition in which polybutene as an adhesive is mixed in a ratio of 3 to 10% by weight, a vinyl acetate content of 6 to 25% by weight, and a melt flow rate of 0.3 to 3 g /
10 minutes the ethylene - the main component vinyl acetate copolymer Polymerization body,
Provided is a stretch film for grass, which is formed by laminating a second layer made of a composition obtained by mixing 3 to 10% by weight of polybutene as an adhesive by molding. In the stretch film of the present invention, the stress at 100% stretching is 50%.
It is preferable that the stress is higher than the stress at the time of stretching, and the shrinkage rate of the stretch film is 4% or less in the direction orthogonal to the longitudinal direction. The linear low density used in the present invention
Degree polyethylene, high pressure low density polyethylene and ethylene
The melt flow of ren-vinyl acetate copolymer
The rate is based on the test method (trial) specified in JIS K 7210.
Based on a test temperature of 190 ° C and a test load of 2.16 kgf)
went.

[0007]

The present invention is constructed as described above, and by adding an appropriate amount of high-pressure low-density polyethylene, carbon or TiO ₂ , and polybutene to the linear low-density polyethylene that is the main component of the first layer, the linear low-density polyethylene is added. High tackiness, weather resistance, shrinkability and the like are imparted while maintaining the tear resistance of the density polyethylene film. On the other hand, by adding an appropriate amount of polybutene to the ethylene-vinyl acetate copolymer as the main component of the second layer, the adhesiveness can be improved while maintaining the excellent elongation stress of the ethylene-vinyl acetate copolymer. By laminating the first layer and the second layer, it is possible to obtain a stretch film having optimum characteristics for packaging grass.

Hereinafter, the present invention will be described in detail. In the present invention, as the α-olefin used for copolymerization with ethylene, for example, butene-1, hexene-
1,4-methylperten-1, octene-1, etc. are mentioned. In the film of the present invention, the melt flow rate of the ethylene-α-olefin copolymer (linear low density polyethylene) used as the main component of the first layer is 0.4 to 3.0 g.
The reason for limiting to / 10 minutes is that if the amount is less than 0.4 g / 10 minutes, the moldability is poor and the fracture occurs, resulting in a decrease in strength, and if it exceeds 3.0 g / 10 minutes, the resin strength is low. This is because it is not suitable for silage film. Moreover, the density is 0.900 to 0.930 g.
/ Cm ³ is the reason why the density is 0.900 g / cm ³
If it is less than 0.93 g / cm ³ , the film is too soft to obtain a good tightening force. On the other hand, if it exceeds 0.930 g / cm ³ , the film becomes too hard, and it is difficult to stretch and the strength decreases. It is generated and is not suitable for packaging.

In the present invention, by adding an appropriate amount of high-pressure low-density polyethylene to the ethylene-α-olefin copolymer, which is the main component of the first layer, the tensile properties suitable as a stretch film for grass are given. High-pressure method low-density polyethylene has little density dependency, but when a melt flow rate of less than 0.2 g / 10 min is used, dispersibility, moldability, and packaging suitability deteriorate, and 5 g / 10
If the time exceeds, the strength will decrease, so 0.2-5g / 1
Limited to 0 minutes.

The mixing amount of the high-pressure low-density polyethylene is 5
-25% by weight. When the mixed amount is less than 5% by weight, the stress at 100% stretching of the film becomes equal to or less than the stress at 50% stretching, and in this case, it becomes a mechanism for stretching the film by 50 to 80%. If it is used for a wrapping machine for wrapping grass, the overlapping parts of the film will be small and the stretching will be uneven, which will cause wrinkles and make it impossible to evenly seal the grass. On the other hand, if it exceeds 25% by weight, the amount of the mixture is too large and the impact strength is drastically reduced, and the film is punctured by the stalks of grass and the like during packaging, resulting in poor sealing.

In the present invention, TiO ₂ or carbon is added as a pigment to the first layer of the stretch film in order to impart hiding power. The hiding power depends on the thickness of the film and the amount of pigment added. For example, in a stretch film having a total thickness of 25μ and a thickness of the first layer of 17μ, the amount of TiO ₂ added to obtain good hiding property is 5.76% by weight, and in the case of carbon, from the balance of hiding property and heat resistance of the film. Experiments have shown that 2.4% by weight is good. When this is applied to a thickness of 15 to 40 μ which is usually considered as a silage stretch film, it is 3 to 10% by weight in the case of TiO ₂ and 1.5 to 5% by weight in the case of carbon. However, considering the strength in the case of TiO _2, the maximum is 7% by weight, and in the case of carbon, 5% by weight is considered to be the limit because the surface temperature rises by sunlight and holes are opened.

In the present invention, polybutene is added to the first layer as an adhesive to give the adhesiveness required for a stretch film for grass. As the polybutene, those having an average molecular weight of 500 to 3,000 are preferable because they exhibit good tackiness. The adhesiveness also depends on the film thickness and the addition amount as in the above pigment, and the addition amount of polybutene is preferably 3 to 10% by weight. If it is less than 3% by weight, poor adhesion will occur, and if it exceeds 10% by weight, the strength will decrease or the adhesion will be too strong, resulting in defects.

On the other hand, the vinyl acetate content of the ethylene-vinyl acetate copolymer, which is the main component of the second layer of the present invention, is 6 to 25.
The reason for limiting the content to 6% by weight is that if the content is less than 6% by weight, the resulting film is hard and difficult to stretch, easily breaks, and the adhesiveness decreases.
On the other hand, if it exceeds 25% by weight, the tackiness of the film surface becomes too large and the strength is lowered. Further, the reason why the melt flow rate is limited to 0.3 to 3 g / 10 min is that the film is less likely to be stretched when it is less than 0.3 g / 10 min and is easily broken at the time of packaging, whereas when it exceeds 3 g / 10 min. This is because the final breaking strength becomes small. The reason for limiting the mixing amount of polybutene as the adhesive in the second layer is the same as in the case of the first layer.

In the stretch film of the present invention, the shrinkage rate is preferably 4% or less in the direction orthogonal to the longitudinal direction. When the shrinkage ratio of the stretch film exceeds 4% in the direction orthogonal to the longitudinal direction, the film width on the outer periphery of the product becomes narrower, and when the film is pulled out, the film inside is pulled out, so the film breaks. Occur.

The stretch film of the present invention can be produced by laminating the first layer and the second layer. As a laminating method, a known inflation molding method described in Japanese Patent Publication No. 2-12187 can be used. In the present invention, for the purpose of improving the yield on an actual commercial basis, the ears and hollow portions removed from the product film are pelletized between the first layer and the second layer to form the first layer component. It is also possible to form three layers by providing an intermediate layer made of a composition in which about 30% by weight is mixed.

[0016]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. In addition, in the following Examples and Comparative Examples of the present invention, each test item was measured by the following methods.

[Tensile properties (50%, stress during 100% stretching)] The tensile test was carried out according to the tensile test of ASTM D882.
However, the test piece was dumbbell-shaped, the upper and lower gripping intervals of the test piece were 40 mm, and 50% and 100% stretching stresses were determined from the strain-stress curve obtained on the chart. [Adhesive strength] On a plate with a flat surface of 100 mm x 100 mm,
The film stretched by 50% in the longitudinal direction of the film was fixed, and the other film was also stretched by 50% in the longitudinal direction and fixed on a plate having a size of 100 mm × 100 mm which was sufficiently adhered. These films were attached so that the back and front were in close contact, and the maximum stress when moving at a speed of 100 mm / min with a plate with a flat surface of 100 mm × 100 mm as the moving surface with an Instron type universal tensile tester Was the adhesive strength. [Tear Test] The tear test was performed according to JIS P8116. [Dirt Impact] Dart impact was performed according to ASTM D1709. [Shrinkage rate in TD direction (shrinkage rate in the direction orthogonal to the longitudinal direction of the film)] Ethylene-α according to JIS Z1709.
-Measured at 90 ° C, which is a temperature near the softening point of the olefin. [Film width (product width over time)] After the product of 1800 m was left in an oven at 40 ° C for 24 hours, the width of the film when the temperature of the film dropped to room temperature was measured. [Packing suitability] Packaging was performed using a grass bale wrapping machine WM1500 type manufactured by Takakita Co., Ltd., and evaluated for the stretched state of the film, the overlapping state of the film, uneven stretching, breakage, and the like. [Total Light Transmittance] It was measured according to JIS K7105.

Example 1 As a composition for the first layer, an ethylene-4-methylperten-1 copolymer (melt flow rate = 0.6 g / 10 min, density = 0.920 g / c)
m ³ ) 61.9% by weight, high pressure method low density polyethylene 1
5.0 wt%, Nisseki Polybutene HV-35 40 wt%
Masterbatch (ethylene-4-methylperten-1 copolymer (melt flow rate = 0.6 g / 10 minutes, density = 0.920 g / cm ³ ) base) 7.5 wt%, Santac (Santec Polybutene 50) 6% by weight, white pigment masterbatch (ethylene-butene-1 copolymer (melt flow rate = 12 g /
10 minutes, density = 0.920 g / cm ³ ) base, TiO ₂
60% by weight, weathering agent CHIMASSORB 944LD
(Nippon Ciba Geigy Co., Ltd.) 3.75% by weight) 9.6% by weight was dry blended, and the screw diameter was 55 φm.
The mixture was kneaded at 180 ° C. with two extruders of mL / D = 28 mm, while an ethylene-vinyl acetate copolymer (melt flow rate = 2.0 g / 10 min, vinyl acetate content =) was used as the second layer composition. 15% by weight) 84.3% by weight, Nisseki Polybutene HV-35 40% by weight Masterbatch 8.7
1 wt% and 7 wt% of Santac (Polybutene 50 wt% masterbatch manufactured by Suntec Co., Ltd.) are dry-blended, and the amount is 1 with an extruder having a screw diameter of 55 mm L / D = 28 mm.
It was kneaded at 80 ° C. Both of them were blown at a blow ratio of 3.6 and a take-up speed of 28 m / min, and the extrusion amount was adjusted so that the ratio of the first layer was 17 μ and the second layer was 8 μ, and an annular die with a gap of 2 mm at the die outlet was formed. The resin was supplied and the resin was extruded in a tubular shape at a die temperature of 180 ° C. to form a film. The composition of the obtained film is shown in Table 1, and the various characteristics described above were investigated and shown in Table 2. As a result, it was found that it has sufficient properties as a stretch film for grass. Also,
When this film was wrapped in a Takara WM1500 wrapping machine for grass wrapping, a very good silage was obtained with few wrinkles in the film.

(Examples 2 to 10, Comparative Examples 1 to 4) As shown in Table 1, the ethylene-α-olefin copolymer of the first layer composition has a melt flow rate, a density, a comonomer type and a high pressure method low density. A film was formed in the same manner as in Example 1 except that the amount of polyethylene added, the melt flow rate of the ethylene-vinyl acetate copolymer of the second layer composition, or the adhesive was changed. Table 2 shows the properties of the obtained film. It was confirmed that, like the film of Example 1, the films of Examples 2 to 10 have sufficient properties as a stretch film for grass. On the other hand, the films of Comparative Examples 1 to 4, which were outside the scope of the present invention, were unsatisfactory in packaging suitability.

(Example 11) The same procedure as in Example 1 was repeated except that the white pigment masterbatch was not mixed and, instead, the carbon 30% by weight masterbatch (the same base as the white pigment) was mixed by 8.0% by weight. A film was formed. The composition of the obtained film is shown in Table 1 and the characteristics are shown in Table 2. As with the film of Example 1, the film of Example 11 was confirmed to have sufficient properties as a stretch film for grass.

Comparative Example 5 The same as Example 2 except that the white pigment masterbatch was not mixed, but 10.0% by weight of a talc 50% by weight masterbatch (the same base as the white pigment) was mixed. A film was formed. The composition of the obtained film is shown in Table 1 and the characteristics are shown in Table 2. When grass was packaged using this film and left to stand outdoors for silage preparation, the grass turned brown and fermentation failure occurred.

Comparative Example 6 The same as Example 2 except that the white pigment masterbatch was not mixed, but 10.0% by weight of natural silica 50% by weight masterbatch (the same base as the white pigment) was mixed. To form a film. The composition of the obtained film is shown in Table 1 and the characteristics are shown in Table 2. When grass was packaged using this film and left to stand outdoors for silage preparation, the grass turned brown and fermentation failure occurred.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

Industrial Applicability As described above, the stretch film for grass of the present invention is suitable for packaging grass using a wrapping machine for grass, suitable for tackiness, impact resistance, shrinkage, and Japanese climate. It has weather resistance, does not cause film breakage during packaging, maintains a good anaerobic state after packaging, and also keeps airtightness for a long time even when left outdoors to prepare silage. Because it can be maintained, you can get good quality silage.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display area B65D 65/40 B65D 65/40 E

Claims (1)

(57) [Claims] 1. A linear low density obtained by copolymerizing ethylene and α-olefin, having a melt flow rate of 0.4 to 3.0 g / 10 minutes and a density of 0.900 to 0.930 g / cm ^3. Polyethylene is the main component, with a melt flow rate of 0.2-5 g / 10 min and a density of 0.916-
0.930 g / cm ³ of high pressure low density polyethylene
~ 25 wt%, 1.5 to 5 wt% carbon as a pigment
Alternatively, the first composition is composed of 3 to 7% by weight of TiO ₂ and 3 to 10% by weight of polybutene as an adhesive.
A layer, with a vinyl acetate content 6-25 wt%, a melt flow rate 0.3 to 3 g / 10 min ethylene - the main component vinyl acetate copolymer Polymerization body, a polybutene as an adhesive 3 to 1
A stretch film for grass, which is formed by laminating a second layer made of a composition mixed with 0% by weight by molding.